In a large mixing bowl, combine softened unsalted butter and light brown sugar. Beat together until light and fluffy, about 2-3 minutes.

Add creamy peanut butter and a room temperature egg to the mixture and mix until smooth and well incorporated.

In a separate bowl, whisk together all-purpose flour, baking soda, and salt. Gradually add this dry mixture to the peanut butter mixture, folding it in gently until fully combined.

Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes.

Preheat your oven to 350°F (175°C). Once the dough is chilled, scoop tablespoon-sized amounts and roll them into balls. Place on a parchment-lined baking sheet.

Flatten each ball with a fork to create a crisscross pattern and ensure even baking.

Bake in the preheated oven for 10-12 minutes until the edges turn golden brown and centers are soft but set.

Let the cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.

Spread creamy peanut butter between two cooled cookies to create a sandwich and enjoy!